In a semiconductor process, is used a method for measuring, with use of a critical dimension SEM (scanning electron microscope), test patterns manufactured on a silicon wafer by altering a dose amount and a focus value of an exposure apparatus to determine a dose range and a focus range for manufacturing a normal pattern. Such method is disclosed in PTL 1. The method is hereinbelow referred to as “a process window analysis.” In a development stage, the process window analysis is used as a criterion of determining an exposure condition and selecting a photosensitive light-receiving resin (hereinbelow referred to as “a resist”) to be applied on the silicon wafer. Also, results of the process window analysis are used for management in a mass production stage and are fed back to the exposure apparatus as needed.
In a recent semiconductor process, the pattern is densified, and the pattern shape is complicated. This makes it difficult to automatically set an optimal process window (e.g., the dose range and the focus range) for all pattern shapes and all pattern layouts in the conventional critical dimension SEM. Accordingly, for the pattern or part of this kind, a method for visually determining whether or not the pattern is a normal pattern and deriving a process window is employed.
To automate the process window analysis for the parts that are difficult to measure, quantification of the pattern shape is required. Examples of a method for evaluating the pattern shape include: methods for evaluating the pattern shape by using a design data of an electronic device as a reference pattern (PTL 2 to 5); a method for evaluating the pattern shape by using a pattern of a good device as a reference pattern (PTL 3); and a method for evaluating the pattern shape by generating a stable reference pattern (PTL 6).